The overall objective of this program project research is to evaluate the role of altered membrane structure and function in the aging process. Membranes are focused upon because of their prime position in integration and regulation of metabolism and thus most physiological activities. Specifically the relationships between possible alterations in membrane structure and function during aging to several aspects of muscle, nervous tissue and adipose tissue function will be investigated. 1) The exploration of the molecular basis for the deficiency of muscle function in the aged by the following approaches: a) Investigation of possible alterations of excitable membranes of muscle during aging. b) Investigations of possible alterations of sarcoplasmic reticulum membranes during aging with particular emphasis on the processes of excitation-contraction coupling and muscle relaxation. c) Investigation of possible alterations in the contractile proteins (actin and myosin) and the modulating proteins (troponin and tropomyosin) during aging. 2) The exploration of the molecular basis of the increased adiposity which develops with age along the following two lines: a) Investigations of possible alterations in the plasma membrane of the adipocyte with particular emphasis on the humoral and hormonal receptor sites and systems involved in fat mobilization. b) Investigations of the possible alterations in the hormone-sensitive triglyceride lipase, the enzyme involved in fat mobilization, and the relationship of changes in this enzyme function to changes in the adipocyte plasma membrane. 3) The exploration of possible reasons for neurophysiologic deficiencies which occur during aging by making measurements on action potential coding patterns and metabolic activities of neurons at a cortical level. These measurements will provide information on the excitable membranes of neurons, the synaptic membranes and the stimulus-metabolic transduction potentialities of the system.